Thanksgiving marks a glorious feast for millions of Americans – year after year.

But this time the holiday comes especially late. This year, Thanksgiving takes place on November 28, less than a month before Christmas.

Here is an explanation of why it happens so late in the month and how often it occurs.

Why is Thanksgiving on the fourth Thursday in November?

Most people associate Thanksgiving with Native Americans and Pilgrims in Plymouth, Massachusetts gathering for a feast, but the current holiday’s origins are a bit more modern.

According to the Center for Legislative Archives, President George Washington designated the last Thursday in 1789 as a “Day of Publick Thanksgivin”, with subsequent presidents issuing similar proclamations on different days of the year.

President Abraham Lincoln issued a proclamation in 1863 declaring the last Thursday in November as the date of the holiday, where it remained until the administration of President Franklin Roosevelt, according to the Center.

Finally, in October 1941, Congress passed a resolution declaring the holiday to occur on the fourth Thursday in November, to avoid falling on the last day of the month, thus extending the holiday shopping season and giving retailers additional time to take advantage of of Christmas-driven sales.

Roosevelt then signed the bill into law, establishing Thanksgiving as a federal holiday.

How often does Thanksgiving occur on November 28?

Since Thanksgiving always takes place on the fourth Thursday in November, it roughly follows a 28-year cycle, interrupted only by centennial and leap years.

Therefore, Thanksgiving will fall on November 28th approximately every five to six years. The next time this will happen is in 2030, but won’t happen again until 2041.

When can the earliest Thanksgiving occur?

The earliest date that Thanksgiving can occur is November 22nd. This last occurred in 2018 and will not occur again until 2029.